As a homeowner, it can be challenging to decide on how to replace your asphalt shingle roof. In general, you’ll have two options—adding another layer to the existing roof or replacing it completely. If you’re leaning towards an overlay instead of a tear-off, you should consider many problems with two layers of shingles first.
Why Multiple Roof Shingle Layers Are Not Ideal
Having more than one layer of asphalt shingles on your roof is not a good idea for several reasons:
1. Excess Weight
Adding a second layer of shingles puts extra weight and stress on the roof decking and framing, as well as the home’s structure. Moreover, it can become problematic in winter—piled-up snow can cause the roof to collapse, especially if there are existing structural issues.
2. Unseen Decking Damage
When overlaying, roofing contractors cannot inspect and assess the deck’s overall condition. There may be extensive rotting underneath, which leads to bigger, more expensive repairs if left unaddressed.
3. Trapped Moisture
Moisture can easily get caught in between shingle layers, causing wood underneath to rot quickly and prematurely.
4. Lack of Leak Barriers
Roofers can only install water and ice leak barriers on the decking. If they overlay rather than remove the old layer, there’s no guarantee your roof can effectively keep out water during rain and snowfall. A roof with a history of leaks is even more vulnerable.
5. Bumpy Surfaces
Asphalt shingles must lay flat to be installed properly. So if your old roof has curled, torn, or damaged shingles, the surface becomes an uneven base for the new shingles. Not only does this make the top layer unattractive, but it also increases the likelihood of future issues.
Other Reasons Why Two Isn’t Necessarily Better than One
If you’re curious about how many layers of shingles can be on a roof, most building codes allow up to two. That is not to say, however, that you should choose this option. If the issues stated above aren’t enough to dissuade you, consider the following frequently ignored long-term disadvantages of a two-layered asphalt shingle roof.
It Has a Shorter Lifespan
An overlay will not last as long as a tear-off because the extra shingle layer traps more heat and moisture. Such issues speed up the deterioration of the structure underneath, meriting costly repairs or full roof replacement.
It Is Costlier
If you think that an overlay will save you money, it won’t in the long run—you’re only delaying the inevitable. When it’s time to strip off all the layers, you’ll likely end up paying twice as much for the removal and disposal of shingles. When you factor in the problems associated with multiple-layered roofs, you’re likely to spend more. If the upfront costs of a tear-off are a barrier, financing options can make it more affordable.
It Affects Home Value
If you plan to sell your home, potential buyers are likely to avoid a property with an overlay since it means they would eventually have to spend for a full roof replacement. This puts you at a disadvantage when negotiating the selling price.
Turn to Us for Reliable Roof Replacement
Some roofers would argue that having two layers of shingles is acceptable. However, professional roofing contractors such as DMG Exteriors, never recommended this method due to the safety and practical reasons outlined above.
If you don’t want problems with two layers of shingles on your new roof, look no further than DMG Exteriors. For over a decade, we’ve installed a range of roofing, siding, and other exterior features in homes across Indiana. We offer quality services at reasonable rates, and we’ve made it easier and more affordable with our financing options.
Get a free quote for our roofing services when you fill out the online form today.